A campaign to highlight the need for LGBT diversity in British boardrooms has boosted its PR firepower by bringing in Capella PR.

OUTstanding in Business, a gay and lesbian executive networking group, is seeking to ensure diversity debates around top-level business influence include LGBT issues.

Launched in June, the group has the backing from the likes of Barclays and Google, as well as BP and its former CEO Lord Browne.

Capella founder Gareth Thomas explained that the work would be led by "a hard business case".

He said: "This is not about a moral argument. This is about saying there’s an economic reason as to why it’s better to be out in business as people are more productive and focused when they are able to be themselves."

The first stage of the campaign will kick off shortly with the Financial Times listing the top 50 most inspiring LGBT senior business executives.

Browne was forced to resign from BP in 2007, earlier than planned, after admitting to lying to a court about how he had met a former boyfriend. He said at the time he had always regarded his sexuality "as a personal matter". He is currently the chairman of energy company Cuadrilla Resources.

Capella's brief will run until the end of the year. It will target national business and trade writers with news stories and strategic research, as well as harnessing social media.

Thought leadership will also be key, with founder of OUTstanding in Business Suki Sandhu positioned for comment alongside other high-profile supporters.